Abstract:With the perennial cutting seedling of Euonymus laxiflorus, E. maackii and E. alatus as experimental materials, we determined the leaf color parameters and related physiological and biochemical indexes of the leaves during the color change period. The changing rules and internal relations of various indicators were discussed, with a prospect to provide a scientific basis for selecting excellent color leaf plants. The results showed that: (1) the values of L*(Gloss brightness) and b*(Yellow/Blue) of E. laxiflorus showed an upward trend, and the value of a* (Red/Green) did not change much. The values of L* and b* of E. maackii increased first and then decreased and the value of a* is on the rise. The values of L* and b* of E. alatus did not changed much and the value of a* is on the rise. (2) The chlorophyll content of the 3 species showed a significant downward trend during the color change period. The relative content of anthocyanins and the value of anthocyanin / chlorophyll of E. laxiflorus were relatively stable while its value of carotenoid/chlorophyll increased. The relative content of anthocyanin and the value of anthocyanin/chlorophyll of E. maackii and E. alatus increased, and their value of carotenoid/chlorophyll remained stable. (3) The phenylalanine ammonia lyase (PAL) activity of the three species showed a downward trend, and the activity of chalcone isomerase (CHI) increased first and then decreased. The activities of peroxidase (POD) and polyphenol oxidase (PPO) of E. alatus remained stable. The POD of E. laxiflorus and E. maackii increased. The PPO of E. laxiflorus remained stable and the PPO of E. maackii showed a downward trend. (4) The mass fraction of soluble sugar and starch of E. laxiflorus and E. alatus increased first and then decreased. The mass fraction of soluble sugar and starch of E. maackii increased. (5) According to the correlation analysis, the yellow color of E. laxiflorus was mainly due to the decomposition of chlorophyll. The red color of E. maackii and E. alatus were mainly due to the synthesis of anthocyanins. Soluble sugar, starch, CHI had a certain effect on the synthesis of anthocyanins. POD promoted the appearance of red leaves. PAL and PPO had no significant relationship with the synthesis of anthocyanins.